2018 Mac Mini - monitor problems

Incredible. After installing Mojave 10.14.6 my screen and my Mac mini started to work perfectly. Everything was perfect until last week when I updated to Mojave 10.14.6 b My problems with my LG restarted again. However, this time the problem is different, my 2018 Mac mini detects the screen and it works right but after 20 minutes the screen flickers. My the only way to solve it has beeb to connect the display to the Mac mini with a HDMI USB-C adapter. Then the problem has been solved.

My recommendation buy an adapter and connect the display through the USB-C connection.

I hope it helps

Sounds exactly like the same problem I had except I didn't have a usb-c cable. Only HDMI.

Weirdly, the way I got it to work was to tap the power button several times while it was loading up. The apple logo then appeared and blank screen went away and never came back. I read this in an earlier post where someone had to do this everytime to get the screen to show up. In my case I only had to do it once and now the fix seems permanent.

To give the complete story I did change my HDMI cable, swap monitors and stop booting from external USB drive. I'm now back to using my original monitor.

I actually think the HDMI port on the Mac Mini 2018 is broken....

Mine was working fine for several months and then suddenly stopped working like everyone else here.

Do yourself a favour....avoid using the HDMI port .... and use the USB-C ports for video until Apple can fix this.

So far this has worked for several people here including myself.

Its still unacceptable that Apple can sell a product with a faulty port and force us to use a workaround solution.

I'm just grateful I don't need all 4 USB-C ports - although already using 3.

Strange as it may seem my 2018 Mac mini has been working flawlesly for a week. HDMI-HDMI. What I did? Reset SMC. I unplugged for 20 seconds and after 5 seconds plug again. Since that moment, there has been no problems. I am really amazed. I think Craptalina is really turning into Catalina.

I hope it works. My OS Catalina Supplemental Update.

Resetting SMC has worked for me (2018 Mac mini connected to TCL 4k tv via HDMI). Spent hours on the phone with support. Said it is a known issue and they are working on a fix. I don't believe them since this question was posted almost a year ago and it has been worse for me since upgrading to Catalina. I do think that they should offer a refund when something this fundamental is broken.

Here's hoping that they have to pay per support call so that my daily calls will wear them down... Never thought I would say this but my inclination is that a PC would be a more reliable option at this point :/

I had the same issue - but now everything runs well!

My monitor 27UD58-B 68,58 cm (27 Zoll) ist connected with the original LG-cable USB-c to Displayport.

FileVault2 ist enabled. Coldboot and restart is OK.

After coldboot the monitor shows Apple-Logo and after some seconds a Login-Screen (unlocking the SSD).

After login Catalina (13.2) booting.

I’ve had my Mac Mini for almost 3 weeks now. When I first got it it had the same problem of not being able to wake up the monitor connected to the HDMI port (HP 32QHD Pavilion) and/or showing purple everywhere then static after a couple of seconds. It is important to say that I also had a USB 3.0 external hard drive case connected to one of the USB ports.

i decided to change the HDMI cable as a last resort before returning it. I also unplugged the external drive as i didn’t want to use it as my main machine anymore. Finally, I set the computer to wake up at 3am since I often go to bed and leave open documents to continue the following day. For several days the machine worked flawlessly, at least until I decide the plug in the external drive again, that once again brought the color problem with the screen going to static after a few seconds. I have tried to use it with and without the USB drive since and the machine still works flawlessly without the external drive plugged in, as soon as I connect it I go back to having monitor issues. I have a DAC connected via USB, it doesn’t seem to affect the monitor in any way.

In short...

• Fancy HDMI 4K certified cable from Best Buy solved the issue for me.
• Some USB peripherals seem to bring issues, some don’t.

Wanted to let everyone know that I updated the Mac mini to 10.15.3 and, after some graphical weirdness during reboots for installation, I haven't had wake from sleep issues yet (I updated on the day of the release). I ran the Mini with my Samsung U32J59x display using HDMI out from Mac to the display, and allowed the computer to sleep as normal (I had turned off sleep in system preferences because it was the only way to have the Mac reliably available). Today, I connected the display to the Razer Core X (with an XFX Radeon 580) via HDMI and again allowed it to sleep when not in use as normal. So far so good; the Mac wakes from sleep as expected. Fingers crossed.

I found out that this happens to various monitors but not all.

I have some LG monitors, and there it happens quite often.

Actually what I have found is that the Mini boots ok, but for some strange reason the screen is not capturing the signal (or the signal is not sent).

But if I wait for 1-2mins and then enter my password, then the desktop appears ok.

They only delete commends with the word that rhymes with “soot.” However... they did fix i, as far as I can tell, with 14.4. Took longer than I wanted but it happened.

I'll go one step further: it screwed up my working system (not 10.15.4 but the update to 14.whatever). However, an SMC reset fixed it. After I recovered from the SMC reset. [sigh]

I bought a new monitor (Dell U3818DW) and it arrives before sending the Mac-mini the repair center. I've made some tests.

1. Connected only the Dell display to the Mac Mini using the USB-C ports, reboot, cold restart, sleep and wake up, no problems.
2. Connected Dell display and Cinema Display, on 2 USB-C ports, reboot, cold restart, sleep and wake up, no problems.
3. Connected Cinema Display on USB-C (after the other tests), reboot, cold restart, sleep and wake up, no problems.

So far, there is no more problems on the Mac Mini not starting, reboot, kernel panic, freezing and so on. For those who are having problems to get an external monitor working with Mac Mini, try to connect other Monitor on the USB-C port, connect your monitor to the USB-C and then connect just your monitor. Can be related to the configuration that the Mac Mini stores from the monitor.

I tried to rollback to version 10.14.0 and the problem persisted. Reinstalling the OS will not work either. It's has been 2 weeks since i bought a new Dell monitor and the problem disappeared. New Dell monitor + Cinema Display working fine and Mac-mini doing all his functions properly (sleep, start, cold start and so on)

I'm still think it's a software problem, not hardware, related to the mac mini and how it stores the information about the monitor. I think it's worth the test, take the mini and test different USB-C and HDMI monitors on a store. After I connected a brand new monitor, the problem was gone.

Hey everyone,

came across this thread as I was having a similar issue with my second monitor not working. I've got 2 LG 4K 32UD59-Bs' hooked up with USB-C to DP cables. Yesterday display 2 stopped working and after much hair pulling and cable switching the fix I found was to turn off the display and with the DP cable plugged in, unplug the power (for the display) and plug it back in. This fixed it for me.

I just returned my 2 day old 2018 I7 mini and ordered a new one. Using it with a new 4K LG 32" monitor. After initial startup was prompted to do 10.14.5 update. SSD is encrypted. After OSX update I would lose video after login and progress bar advanced about 25%. Monitor would go into power save mode. Often took 2-3 reboots to get the machine to start. Apple support via phone wanted to reinstall OSX via network install but the machine would not boot to a point where the install would start. They had me take to the local Apple store where they wiped the SSD and did a clean install of 10.14.5. Worked ok when I got home and powered it down for the night, This morning it took four tries to boot from cold start. Ran it for 20 minutes, powered it down and tried 20 minutes later. Still took two tries from a cold start. Called phone support again and they recommended returning the unit and ordering a new one which I did today. I'm running TB3 for the monitor connection. When the new one arrives I'm not going to use SSD encryption and try HDMI instead of TB3. So far very disappointed in this product and I'm pretty sure their is an issue with video driver and/or the time it takes for encryption to access the SSD. Too many others are seeing similar issues with 10.14.5.